Mercury switch controller



1.. P. DEL VECCHIO, JR. ET AL 3,482,196

Dec. 2, 1969 MERCURY SWITCH CONTROLLER 2 Sheets-Sheet 1 Filed Sepc. 28, 1967 INVENTOR. LEONAPO Del VECCH/O Me:

WALTER E,LE'VINE ATTORNEY D 1969 L. P. DEL VECCHIO, JR, T AL 3,482,196

MERCURY SWITCH CONTROLLER Filed Sept. 28, 1967 2 Sheets-Sheet 2 ALTER E LEVIN ATTOPA/EY United States Patent MERCURY SWITCH CONTROLLER Leonard Patrick Del Vecchio, Jr., Trumbull, and Walter E. Levine, Handen, Conn., assignors to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware Filed Sept. 28, 1967, Ser. No. 671,438

Int. Cl. H01h 37/42, 29/00; G01d 13/26 US. Cl. 337322 Claims ABSTRACT OF THE DISCLOSURE A control switch instrument including a mercury tilt switch operable between electrically open and electrically closed position by means of a condition responsive force transmitting unit. Mechanical change in the connection between the force transmitting unit and switch support permits optional and interchangable operation of the switch for either normally open or normally closed requirements.

Background of the invention (1) The field of art to which the invention pertains includes the art of electricity, circuit makers and breakers as specifically including the art therein pertaining to switches operative by fluid pressure or other force and motion producing devices.

(2) Condition responsive switches for various control purposes are well known in the industry and are available from many sources of manufacture. Common among the switches are those in which the switching element comprises a mercury tilt bulb. Opening and closing of a connected electrical circuit with this type element is effected by the gravity shifting of a mercury glob to and from the contacts in response to tilt movement from either a pressure or temperature sensitive element. Typical devices exemplifying this art are Patents 1,734,016; 2,251,385; 1,762,491, each of which employs a mercury switch actuated in response to a particular mechanism for making and breaking the circuit.

Because these switches are in such Wide commercial use, they are mass produced and readily available to meet the requirements of the market they are to serve. However, control situations for which these switches are employed require that the switch be either normally open, i.e. in open circuit relation in the absence of a pre-applied closing force, or be normally closed, i.e. in closed circuit relation in the absence of a pre-applied opening force. Accordingly, it has been necessary for manufacturers to make and for suppliers to stock separate switches providing both types of switching action to satisfy customer needs ondemand since it has not been known how to conveniently interchange the switching action from one to the other. Moreover, the need to reverse operation frequently arises on site and must be performed by maintenance and service personnel.

Various techniques toward this end have been tried including the obvious of instrument disassembly and turning the mercury bulb end for end. Yet, another approach by prior art techniques for the purpose of eliminating otherwise duplicate stock has been to provide electrical leads on each end of the mercury bottle whereby the appropriate leads can be selected or interchanged to meet the particular needs of the customer. This, however, has not proved popular because of the additional manufacturing expense rendering the product less cost competitive when compared to similar products without this added feature. Hence, there has therefore been a long felt need for a switch of this type having easily interchangable operation without added expensive components and which can be readily effected by maintenance or service personel on site with a minimum of effort and expenditure of time.

Summary This invention relates to control instruments and particularly to electrical control switches operative in association with a condition sensitive element such as a Bourdon tube, bi-metal thermostaticelement or the like. More specifically, the invention relates to a control switch of the mercury bulb type operative in response to a force transmitting unit and which is capable of having its switching operation from between normally closed and normally open operation easily and inexpensively interchanged requiring only a minimum of time and labor to effect. In accordance herewith, a switch is constructed with the mercury tilt bulb on a pivotal support which operatively connects to the force transmitting unit. By a very simple interchangable connection in the mechanical linkage between the bulb support and the drive connection thereto, switch operation can be reversed without disturbing the mercury bulb per se or its electrical leads and without duplicate and opposite leads being provided. Accordingly, by means of the invention hereof, the prior problems with respect to achieving this result are overcome with a single unit which can simply be switched from one operating condition to the other Without the difficulty or expense associated in effecting simi lar changes in prior art devices.

It is therefore an object of the invention to provide a novel control switch constructed with the capability of easily interchangable normally closed and normally open operational response.

It is a further object of the invention to provide a novel mercury tilt switch in a condition responsive control instrument capable of effecting the aforesaid interchangability simply and easily with a minimum of time and expense.

Brief description of the drawings FIGURE 1 is a front view partially broken away illustrating an exemplary control instrument employing a switch operable in accordance with the invention hereof;

FIGURE 2 is a sectional elevation taken substantially along the lines 22 of FIGURE 1;

FIGURE 3 is a sectional view taken substantially along the lines 33 of FIGURE 1;

FIGURE 4 illustrates the relationship of the component elements for normally open operation of the switch;

FIGURE 5 illustrates the relationship of the component elements for normally closed operation of the switch;

FIGURE 6 is an isometric view of the switch connecting clip; and

FIGURE 7 is an enlarged fragmentary view of the beam mounting for either operational position of the switch.

Referring now to FIGURES 1-3, there is illustrated a condition responsive switch which may generally be of a type disclosed in patent U.S. 3,225,622 and incorporated herein by reference although not to be considered a limitation of the invention hereof. The instrument 10 is comprised of a casing 11 including a generally cup shaped housing 12. Enclosed in the front open end of the housing is a transparent glass or crystal 13 secured by means of bezel or ring 14. Disposed within the housing is a backplate 18 secured to the rear housing wall and containing mounted dependent thereon a fitting or socket 19 extending externally of the housing and adapted to be connected to a source of fluid pressure to which the instrument is to respond.

Within the casing is supported a Bourdon tube connected in fluid communication at its fixed end to socket 19 for receiving fluid pressure supplied thereto. The free end of tube 20 is connected to one end of a pivot link 21 which has its other end connected via a pin 22 and slip washer 23 to a beam 26 which is in turn operatively connected to switching element or mechanism 25. As can be seen, the beam 26 comprises a generally elongated sheet metal member having an elongated slot 27 extending longitudinally thereof. Mounted on this portion of the beam is a clamp 28 having a generally U-shaped cross section to embrace the beam and is held thereon by clamp screw 30 extending through the slot 27 and which can be adjustably located therein. The screw 30 includes an extension in the form of a pin 32 supported at its opposite end in a secured bracket 33 to provide a fulcrum pivot for the beam in response to forced movement transmitted from the Bourdon. Also, provided in the instrument are arms 35 and 36 by which the operational set points of pointers 37 and 38 respectively can be translated to the switch operation as more clearly and fully described in the aforementioned Patent 3,225,622.

Switch 25 includes a conventional mercury tilt bulb element 40 from which extends electrical leads 41 and'42 to be switched via the mercury glob 43 contained in the envelope. The bulb element is supported within a switch bracket assembly that includes a pivotal base portion 45 of a generally U-shaped configuration having depending legs formed with aligned apertures receiving a fixed shaft 47 secured by a slip washer 49 and defining the pivot axis thereof. Supporting the mercury bulb 21 from the base is an embracing bracket 48 which extends generally upward from the base including opposite sides 52 and 53 which serve as pivot stops or abutments by engagement against a fixed intervening shaft 54. Pivoting of the base in order to tilt the mercury bulb for effecting switching operation is produced by means of the leftmost end (as viewed in FIGURE 1) of beam 26 connected theretoas the beam responds to movement emanating from the Bourdon tube via link 21.

In accordance with the invention hereof as further illustrated in FIGURE 4-7, beam 26 can be connected to bracket base 45 at either of two optional locations thereon depending on whether the preselected choice of operating the switch is either normally open or normally closed. For this purpose, base 45 includes aperture pairs 56 and 57 aligned parallel to each other through the opposite spaced legs of the base and each axially parallel to opposite surfaces of pivot shaft 47. Connection of the beam to the base through either aperture is made via a hand compressible diverging spring clip 59 having side faces 60 and 61 each containing transversely aligned apertures 62 and 63 respectively through which to receive the beam end. At the topmost portion of the clip is an encircling section 64 which receives and embraces a removable pin 66 supported through opposite legs of the 'base 45 in either of aperture pairs 56 or 57. It is to be noted that the leftmost end of the beam is of reduced dimension and has spaced guide notches 67 and 68 formed therein along its lower edge. When the diverging ends of the clip are hand or tool compressed inwardly together, the beam can be moved laterally free through the apertures 62 and 63. With the beam removed the clip when released is free to expand beyond the position of normal restraint imposed by the beam and until the pin 66 is released from its grip. Being free of the clip, the pin can be easily removed by pliers or fingers and be relocated to the other aperture pair. When released however to its extended form against the beam, the clip is expanded to span or straddle the appropriate notch and secure the lateral beam relation with respect to the axial location of a pin 66 gripped tightly in section 64. Therefore, whichever connecting base aperture pair is employed, the beam leverage and consequently the accurate calibrated response from the Bourdon-tube is maintained and ensured by the clip location extending into a beam gripping relation on both sides of the appropriate guide notch.

Normally open, operation of the switch is effected in the manner illustrated in FIGURES 1 and 4 with the pin 66 in the aperture pair 56 and the beam secured by the clip spanning the notch 67. As can be seen, both the beam pivot and the switch pivot are in the same counterclockwise direction as shown by the arrows in FIGURE 4 in response to counterclockwise movement of the Bourdon. Reversed, normally closed, operation of the switch is produced by mounting the clip 59 to the base at aperture pair 57 as illustrated in FIGURE 5. As indicated by the arrows in this latter figure, the beam and switch pivot oppositely relative to each other with the former yet moving counterclockwise and the latter clockwise.

To interchange operation, clip 59 is hand or plier compressed at its lowermost diverging end to permit release of the beam after which pin 66 is simply removed and replaced in the other of aperture pairs 56 or 57. The clip is then again similarly compressed to receive the beam and be extended at the notches 67 or 68. This therefore converts switch operation simply and easily without disturbing the mercury bulb per se or in any way requiring duplicate leads at the opposite bulb end as has been conventional in the prior art.

By the above description, there has been disclosed a novel control instrument in which operation of a mercury tilt switch can be readily converted from between normally open and normally closed operation by an easy hand operation of interchanging a simple mechanical linkage. This therefore achieves a result long sought in industry whereby to eliminate the tedious and expensive operations and/or added elements which have been required heretofore. Whereas the invention has been principally described in conjunction with a pressure responsive Bourdon tube, this is not to be considered as a limitation. Rather, it should be apparent that the invention hereof can be utilized with any well known force transmitting unit including linkage actuated by hand.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from-the scope thereof, it is intended that all matter contained in the drawings and specification shall be inte-rpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A condition responsive control instrument comprising in combination:

(a) a mercury tilt switch having an electrically open position, an electrically closed position and leads for connection to an electrical circuit;

(b) switch support means pivotally mounted for movement sufilcient to tilt the switch thereon between said electrically closed and open positions;

(c) a force transmitting unit movably operative in response to condition changes from a control setting; and

(d) connecting means operably interconnecting said force transmitting unit to said switch support means for effecting pivotal movement thereof between said electrically closed and open switch positions in response to operative movement of said force transmitting unit, said connecting means having interchangeable connection arrangements including a first arrangement in which the switch on said support is operative as normally open and a second arrangement in which the switch on said support is operative as normally closed.

2. A condition responsive control instrument according to claim 1 in which said force transmitting unit comprises a Bourdon tube movable in response to changes in a fluid pressure input thereto.

3. A condition responsive control instrument according to claim 1 in which said connecting means includes a pivotal beam secured connected from at said switch support means to toward said force transmitting unit.

4. A condition responsive control instrument according to claim 3 in which said interchangeable connection arrangements comprises a removable pin locatable in said support oppositely with respect to the pivot axis of said support for effecting a connection between said connecting means and said support.

5. A condition responsive control instrument according to claim 4 in which said interchangeable connection arrangements include a clip to secure said beam to said pin, said clip having a central portion extending to at least partially surround said pin and walls diversingly extended therefrom, said walls having oppositely aligned apertures therein through which to laterally receive a beam portion to be secured and being compressible toward each other to permit freedom of beam movement through its apertures.

6. A mercury tilt switch for the making and breaking of an electrical circuit comprising in combination:

(a) a mercury tilt bulb having leads for connection to a circuit in which it is to be employed;

(b) bulb support means pivotally mounted for tilting the bulb thereon between said electrically make and break positions;

(c) actuating means operatively connected to said bulb support means to effect pivotal movement thereof between the electrically make and break positions of the bulb thereon; and

(d) means permitting interchangeability between connecting locations of said actuating means to said support means to preselect between normally open and normally closed operation of said switch in correlation to the operating condition of said actuating means.

7. A switch according to claim 6 in which said actuating means comprises an elongated beam pivotal in response to a condition change.

8. A switch according to claim 7 in which said beam is connected to said support by connecting means comprising a removable pin locatable in said support oppositely with respect to the pivot axis of said support.

9. A switch according to cairn 8 in which saild connecting means includes a clip securing said beam to said pin, said clip having a central portion extending to at least partially surround said pin and walls divergingly extended therefrom and resiliently compressible toward each other, said walls having oppositely aligned apertures therein through which when compressed toward each other to laterally receive a beam portion to be secured with freedom of beam movement through its apertures.

10. A switch according to claim 9 including a Bourdon tube connected to said beam at a location displaced from where said beam is secured to said pin for pivoting said beam in response to a condition change.

References Cited UNITED STATES PATENTS 1,630,586 5/1927 Smith 20081.8 1,657,681 1/1928 McCabe 20081.8 X 1,704,371 3/1929 Phelan 20081.8 2,415,034 1/1947 Parker 20081.8 3,278,703 10/1966 Ackerman 200-81.8

BERNARD A. GILHEANY, Primary Examiner H. B. GILSON, Assistant Examiner US. Cl. X.R. 

